<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form method="get" action="userServlet">
    用户名：<input type="text" name="username"> <br>
    <input type="submit" value="校验">

</form>

</body>
</html>